Tire with injection molded white sidewall and method and apparatus for producing the same

ABSTRACT

A pneumatic tire includes a strip of white rubber which is added to the otherwise black tire sidewall. The strip is molded separately from the other tire components and is added to the unvulcanized tire at the tire curing press. The strip is pressed into a recess in the sidewall forming surface of the upper tire mold half by a carrier ring which swings into the tire press with the green tire loader. The strip of white rubber is then affixed to the tire during molding of the tire.

This application is a division of application Ser. No. 08/220,279, filedMar. 30, 1994 which issued as U.S. Pat. No. 5,454,894 and priordivisional application Ser. No. 08/466,581 filed Jun. 6, 1995, now U.S.Pat. No. 5,653,840.

This invention relates to a pneumatic tire having a sidewall whichincludes a strip or insert of a different color than the rest of thetire sidewall and which is affixed to the outer surface of the sidewallthrough an innovative method and apparatus. In the manufacture of radialtires known as "white sidewall tires", it has been necessary tomanufacture the rubber used in the white-colored white sidewallseparately from the rubber used in the rest of the tire. Because thetire components other than the white sidewall utilize rubber containingcarbon black, these components are black in color. In order to obtainthe desired white appearance of the white sidewall, white-colored rubberhad to be manufactured and processed in equipment different from theequipment used to process rubber containing carbon black. Therefore,even though the white sidewall portion of the tire comprised a verysmall portion of the tire, essentially duplicative rubber processingequipment was required in order to produce the narrow strip ofwhite-colored rubber.

It has been found that the same white sidewall appearance can beobtained through a different and innovative manufacturing method andapparatus resulting in a different and innovative white-colored stripwhich provides equivalent or superior performance at a lower cost.

SUMMARY OF THE INVENTION

In accordance with one aspect of the invention, there is provided a tiresidewall having an inside and an outside annular groove which defines anannular strip therebetween. The annular groove is of different materialthan the rest of the sidewall. One side surface of each groove exposesthe strip material and the other side surface exposes the sidewallmaterial.

In accordance with another aspect of the invention, there is provided apneumatic tire having a carcass with a pair of bead portions. A tread isdisposed radially outwardly of the carcass and has a ground-contactingsurface.

A pair of sidewalls extend radially inwardly from the tread along outersurfaces of the carcass toward the bead portions. The sidewalls haveouter surfaces extending from the tread radially ground-contactingsurface to the bead portions. A strip is affixed to the outer surface ofone of the sidewalls. The strip is made from a different elastomericcompound than an elastomeric compound of the sidewall. The strip is of adifferent color than the elastomeric compound of the sidewall. Forexample, in the preferred embodiment, the elastomeric compound of thestrip is white while the elastomeric compound of the tire is black. Theouter surface of one of the sidewalls includes an annular groove havingwalls and a base. The strip is affixed to the base of the groove in theouter surface of the sidewall. The strip has side surfaces, a topsurface and a bottom surface. The top surface of the strip is wider thanthe bottom surface. The side surfaces of the strip have indentationsnear the bottom surface. The strip may be molded, such as by injectionmolding. The side surfaces of the strip make an angle of between 45° and75° with the top surface of the strip. In one embodiment, the sidewallincludes a stain barrier which is positioned inwardly of the strip.

In accordance with another aspect of the invention, there is provided amethod for building a pneumatic tire including the steps of:

(a) assembling unvulcanized components of the pneumatic tire including asidewall;

(b) building the unvulcanized components of the pneumatic tire into avulcanized tire;

(c) preforming an annular strip;

(d) affixing the strip to said unvulcanized sidewall as of the last stepof assembly of said unvulcanized tire by pressing the unvulcanizedsidewall and strip of the unvulcanized pneumatic tire against a sidewallsurface of the tire mold;

(e) vulcanizing the strip and the unvulcanized pneumatic tire.

In one embodiment of the invention, the affixing of the strip includesthe steps of:

(a) loading the strip into a mounting means for mounting the strip intoa recess in a sidewall forming surface of the tire mold;

(b) moving the mounting means and strip to the sidewall forming surface;and,

(c) pressing said strip into the recess.

In accordance with another aspect of the invention, there is provided amethod of loading an elastomeric strip into a tire mold comprising thesteps of:

(a) loading the strip into a mounting means for mounting the strip in arecess in a sidewall forming surface of the tire mold;

(b) moving the mounting means and strip to the sidewall forming surface;

(c) registering the mounting means against the mold; and,

(d) pressing the strip into the recess.

In accordance with another aspect of the invention, an apparatus isprovided for applying a strip to an outer surface of a sidewall of apneumatic tire, the apparatus having a tire mold which in turn has asidewall forming surface to form a sidewall of the pneumatic tire. Thesidewall forming surface has a recess adapted to receive the strip. Theapparatus further has mounting means for mounting the strip in therecess and loading means for loading an unvulcanized pneumatic tire inthe tire mold. The apparatus also includes pressurizing means forpressurizing an interior of the tire. The sidewall forming surfaceincludes spaced-apart rings extending outwardly from the surface of thesidewall forming surface. Each one of the spaced-apart rings has an edgeand each edge has retention means for retaining the strip. The retentionmeans includes an angled interior side of the ring. The apparatusfurther includes lifting means for lifting the mounting means intoengagement with the sidewall surface of the tire mold. The apparatusalso includes a tire vulcanizing press which has a press beam having anopening. The lifting means is affixed to the press beam through theopening in the press beam. The lifting means includes a center rod andan adjustable stop which is slidably affixed to the center rod. Theadjustable stop is slidably adjustable along the center rod toaccommodate molds of different thicknesses. The mounting means is notmechanically attached to the lifting means but is selectively lockablethereto. The mounting means includes a bead stop, the bead stopregistering the mounting means against a top bead ring in the mold. Themounting means also includes pushing means for pushing the strip intothe recess. The pushing means pushes the strip into the recess after thebead stop has registered the mounting means against the top bead ring.The mounting means includes centering means centering the pushing meansagainst the sidewall forming surface of the tire mold. The centeringmeans includes a cylindrical ring having an angled upper surface whichcooperates with an angled lower surface of the pushing means to centerthe mounting means.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of one-half of a tire incorporating astrip according to the invention.

FIG. 2 is an enlarged fragmentary cross-sectional view of a tiresidewall incorporating a strip according to the present invention.

FIG. 3 is a plan view of one embodiment of a strip according to theinvention.

FIG. 4 is a cross-sectional view of a strip according to the inventiontaken along line 4--4 of FIG. 3.

FIG. 5 is a plan view of a carrier ring according to the presentinvention with parts being broken away to show one of the support arms.

FIG. 6 is a front cross-sectional view of a carrier ring assembly andtire loader shown in FIG. 5 showing a green tire on the loader and theupper and lower molds.

FIGS. 7 and 8 are a partial front sectional views of the carrier ring ofFIG. 6, illustrating different positions of the carrier ring in theprocess of inserting the strip into the recess of the tire mold.

FIG. 9 is an enlarged fragmentary cross-sectional view of the carrierring, the lifting means and the sidewall forming surface of tire press.

FIG. 10 is a diagrammatic cross-sectional view of a modified form ofcarrier ring.

FIGS. 11, 12 and 13 are enlarged fragmentary cross-sectional views ofthe sidewall forming surface of the tire mold, the strip and the carrierring showing different steps in the process of shaping and vulcanizingthe strip.

DESCRIPTION OF THE EMBODIMENT

With reference to FIG. 1, a cross-sectional view of one-half of a tire10 according to the invention is shown. The overall construction of thetire 10 is not a part of the invention although it will be describedhere in order to provide an explanation of the general environment inwhich the invention operates. The tire 10 includes a carcass 12 having apair of bead portions 14 respectively. A tread 18 is disposed radiallyoutwardly of the carcass 12. The tread has a ground-contacting surface22. A pair of sidewalls 24 extend radially inwardly from the tread 18along outer surfaces of the carcass 12 toward the bead portions 14. Thesidewalls 24 have outer surfaces 26 which extend from the tread radiallyground-contacting surface 22 to the bead portions 14. In a preferredembodiment, a stain barrier 30 may be incorporated into a sidewall 24 ofthe tire 10. The stain barrier 30 prevents the black color of the tiresidewall 24 from bleeding through to a white sidewall strip 34.

In a conventional tire, the white sidewall is made of conventionalelastomers which do not contain carbon black, the black-coloredsubstance which gives tires their black color. Carbon black is a verypervasive substance, coloring nearly everything it touches. In order tomake a white sidewall elastomer with the desired pristine whiteness,separate Banbury mixers, separate mills, and generally separatemanufacturing and handling equipment is required to manufacture andprocess the white elastomer. As such, even though the white sidewall isa very small part of the tire and adds no performance characteristics orstructural strength to the tire, it adds a very significant element tothe cost of the tire, due to the difficulty in processing andmanufacturing it. Nonetheless, the appeal of white sidewall tires toconsumers is such that white sidewalls have remained an importantelement in many pneumatic passenger tires. The present inventionprovides a tire 10 with equivalent or superior appearance withoutrequiring the large-scale Banbury mixers, mills, and other manufacturingand handling equipment necessary to manufacture a white sidewall tire byconventional methods.

With continuing reference to FIG. 1, a strip 34 is affixed to the outersurface 26 of one of the sidewalls 24. The strip 34 is comprised of aelastomer which, in a preferred embodiment, may be injection molded in aring shape and is added to the rest of the tire components in the tiremold just prior to vulcanization, rather than being built into the tire10 at the tire building machine along with the rest of the components.The method and apparatus for manufacturing, loading, and assembling thetire 10 as described will be discussed later in this specification.

With reference to FIGS. 1-4, the configuration of the strip 34 will bedescribed. In FIG. 2, the portion of the tire sidewall 24 which receivesthe strip 34 is shown in an enlarged view. First and second grooves40,42 define a plateau 44 on the outer surface 26 of the sidewall 24.Each of the grooves 40,42 has a base. The first groove 40 has a radiallyouter wall 48 and radially inner wall 50 while the second groove 42 hasradially outer wall 52 and radially inner wall 54. The radially outerwalls 48,52 of each of the grooves 40,42 expose different materials thando the radially inner walls 50,54. For example, the radially outer wall48 of the first groove 40 exposes sidewall 24 while the radially innerwall exposes strip 34. It is also important to have a narrow groove sothat the interface between the strip and tire body is not exposed.

In the preferred embodiment, the grooves 40 and 42 are about 0.03 inches(0.0762 cm) wide and the radially inner wall 50 of the first groove 40and the radially outer wall 52 of the second groove 42 each make anangle of between 45° and 75° with a plane containing the plateau 44 orwith a plane containing the top or outer surface 60 of the strip 34. Inthe preferred embodiment, the angle is 60°.

With reference to FIG. 3, the strip 34 is shown as an annulus or ring.This is the preferred configuration of the strip 34 although, dependingon the visual effect desired, this strip could be made up of severalsegments, or of a single ring of varying widths or configurations.

With reference to FIG. 4, the strip 34 of FIG. 3 is shown incross-section. The strip includes a top or outer surface, a bottom orinner surface, and side surfaces 64,66. When in place on the tiresidewall 24, the top or outer surface 60 is axially outward of thebottom or inner surface 62 and one of the side surfaces 64,66 isradially outward of the other.

The strip 34 is preferably made of an elastomeric compound according toU.S. Pat. Nos. 4,967,818 and 5,049,220 to Gartland et al., which areincorporated herein by reference in their entireties.

PREFERRED METHOD AND APPARATUS

With reference to FIGS. 5-13, the apparatus and method used to build atire incorporating the strip 34 will be described.

With particular reference to FIGS. 5-9, the one embodiment of a mountingmeans for mounting the strip 34 on a tire mold 82 is illustrated. Inthis embodiment, the mounting means includes a carrier ring 70. Afterthe strip 34 is molded, it is loaded into the carrier ring 70 to beaffixed to a sidewall forming surface 126 of the tire mold 82.

In this embodiment, the carrier ring 70 is mounted on an intermediateplate assembly 182 carried on loader 94 and selectively swingable aboutaxis 72 to carry it about rod 74 which has a centerline coincident withaxis 72. As shown in FIG. 6, the carrier ring 70 is supported on a greentire loader 94 and swings into the tire press 84 between the open moldhalves 176 and 178 when the green tire 180 is being loaded.

With continuing reference to FIGS. 5-9, one of the important aspects ofthe invention is the method and apparatus utilized to accuratelyposition the strip 34 in proper location in the top half 176 of the tiremold 82. In the preferred embodiment, first and second registering meansare utilized for rough and fine registering of the strip 34 against thesidewall forming surface 126 of the tire mold 82.

The first registering means which includes the lifting of the tireloader 94 registers the intermediate plate assembly 182 against pins 78in the upper mold half 176. The plate assembly 182 has alignment holes154 which receive the pins 78 to roughly register the carrier ring 70relative to the top mold half 176 of the mold 82.

A second registering means provides a more precise adjustment,accurately placing the carrier ring 70 in the proper location uponlifting of the ring by pistons in cylinders 156 mounted on the plateassembly 182. The second registering means includes a bead stop 102 onthe carrier ring 70 which registers against a top bead ring 104 in thetop mold half 176 of the tire mold 82. The second registering meansprovides a fine adjustment to very accurately place the strip 34 in themold 82.

The sequence of operation for this method of registering the strip 34 isillustrated in FIGS. 6-8. With reference first to FIG. 6, the carrierring 70 is shown in its location at the top of tire loader 94 mounted onthe intermediate plate assembly 182 affixed to the top of the tireloader 94 by three spacer posts 184. The loader 94 lifts the plateassembly 182 until pins 78 attached to the tire mold 82 register withinholes 154 of the plate assembly 182. This registering provides thecoarse adjustment registering discussed above.

With reference to FIG. 7, the next step in applying the strip 34 to thetire mold 82 begins when a first set of cylinders 156 moves the carrierring 70 toward the upper half of the tire mold until a bead stop 102registers against the top bead ring 104, as illustrated in FIG. 8. Withreference to FIG. 9, after the second registering procedure, or fineregistering procedure, is complete and the bead stop 102 is in properlocation against the top bead ring 104, a second set of cylinders 164push the strip 34 against the sidewall forming surface 126 of the tiremold 82. In the preferred embodiment, the travel of the carrier ring 70due to the action of the second set of cylinders 160 is approximately0.807 inches. With reference to FIGS. 7 and 8, the strip 34 has beenaccurately placed just beneath the portion of the sidewall formingsurface 126 to which the strip 34 should be affixed. As illustrated inFIG. 8, after the first registering process illustrated in FIG. 7 andthe second registering process illustrated in FIG. 8 is complete, athird set of cylinders 164 are activated, pushing a pusher ring 98upwardly a distance of approximately 0.185 inches (0.480 cm.) until thestrip 34 comes into contact and adheres to the sidewall forming surface126 of the tire mold 82. With reference to FIG. 9, the apparatus andmethod is shown in a greatly enlarged view. The pusher ring 98 has aconduit 168 for communicating a vacuum from a vacuum channel 166 to thestrip 34. The vacuum operates on strip 34 through the conduit 168 tohold the strip 34 on pusher ring 98. The sidewall forming surface 126 ofthe mold 82 is heated while in the tire press 84, and after the pusherring 98 has pushed the strip 34 against the sidewall forming surface126, the strip 34 tends to stick to the sidewall forming surface to adegree that the pusher ring 98 can be withdrawn from the strip 34 by thesecond set of cylinders 160 without discontinuing the vacuum applicationthrough conduit 168 to the channel 166.

With reference to FIG. 10, a second embodiment and method of registeringthe strip 34 includes a carrier ring 70', the upper mold half 82' andpress 84'. The carrier ring 70' is supported on centering rings 88'mounted on the top surface 90' of the tire loader 94'. The strip 34' iscarried by pusher ring 98' which in turn is mounted on carrier ring 70'.Instead of lifting the carrier ring 70' to the upper mold half 82' bycylinders 156, as shown in FIGS. 6,7 and 8, the carrier ring 70' islifted to the tire press 84' by a center rod 112. The center rod 112 isattached to the tire press 84' by a cylinder 122 mounted on the toppress beam 110 and extending through an opening 106 in the top pressbeam. The carrier ring 70' is releasably held on center rod 112 whichextends through opening 106 and a guide bushing 114. Mounted on centerrod 112 is adjustable stop 118. The adjustable stop 118 is slidablyadjustable along the center rod 112 to accommodate tire molds 82' ofdifferent thicknesses.

In this embodiment, the carrier ring 70' is lifted up to the tire mold82' by the high temperature pneumatic or hydraulic cylinder or a rackand gear lifting device (collectively referred to as 122) which liftsthe carrier ring 70' by center rod 112. The carrier ring 70' is liftedupward toward the upper mold half 176' until the strip 34' is near thesidewall forming surface 126' of the mold 82'. At this point, the strip34' is pushed into recess 96 in the tire mold 82' by suitable pushingmeans. In the preferred embodiment, the pushing means includes a pusherring 98' which pushes the strip 34' into the recess 96. Prior to thepusher ring 98' pressing the strip 34' into place, the pushing means isregistered in a defined position by bead stop 102' registering against atop bead ring 104' in the mold 82'.

With reference to FIGS. 10-13, enlarged views of a portion of thesidewall forming surface 126 of the tire mold 82 are shown. A pair ofspaced apart rings 130,132 extend radially inward from the sidewallforming surface 126. When the pusher ring 98 presses the strip 34 intooperative association with the sidewall forming surface 126, the stripis affixed to the sidewall forming surface between the spaced apartrings 130,132. With reference to FIG. 12, during the tire vulcanizationprocess, the strip 34 flows and conforms itself to the space between thespaced apart rings 130,132 eventually adopting the configuration shownin FIGS. 12 and 13. With reference to FIG. 13, the strip 34 is shownafter it has been completely adhered to the outer surface 26 of sidewall24.

With reference to FIG. 11, the interior sides 134,136 of rings 130,132respectively are sloped so that an angle x between interior sides134,136 and surface 144 of the sidewall forming surface 126 creates theconfiguration of the strip 34 shown in FIGS. 12 and 13 wherein theinterior sides extend outwardly and form overhanging surfaces at theedges of the strip. In the preferred embodiment, the angle x is between45° and 75° with the most preferred angle being 60°.

With continuing reference to FIGS. 11-13, the rings 130,132 have arounded, bulbous configuration at the edges 150 which creates therounded groove 40,42 shown in FIG. 2. This provides for obscuring theinterface between the strip 34 and plateau 44 as described heretofore.At the edges of the first groove 40 and second groove 42 ribs 186 and188 may be formed projecting outward from the outer surface 26 of thesidewall. The ribs 186 and 188 or another projection from the outersurface 26 may provide scuff resistance to protect the white sidewallstrip 34. The ribs 186 and 188 also further obstruct viewing of the sidesurfaces 64,66 of the strip 34. Also the top surface 60 is wider thanthe bottom surface 62. Because the top surface 60 is radially outward itis the portion of the strip 34 most easily seen by an observer. Becausethe top surface 34 is wider than the rest of the strip 34, the sidesurfaces 64,66 are difficult to see, since the observer of the tire 10generally is looking in the direction generally perpendicular to the topsurface 60. In this way, the side surfaces 64,66, as well as theinterface between the strip 34 and the plateau 44 are obscured by thewide top surface 60.

While certain representative embodiments and details have been shown forthe purpose of illustrating the invention, it will be apparent to thoseskilled in the art that various changes and modifications may be madetherein without departing from the spirit or scope of the invention.

What is claimed is:
 1. A tire sidewall, of a sidewall material having aninside annular groove and an outside annular groove defining an annularstrip therebetween of a strip material, said sidewall material and saidstrip material being different materials, each said annular groovehaving side surfaces, one of said side surfaces of each said annulargroove exposing said strip material, the other of said side surfaces ofeach said annular groove exposing said sidewall material, each of saidside surfaces of each said annular groove exposing said strip materialan having an interface between said sidewall material and said stripmaterial and said annular strip having an outer surface and an innersurface with said outer surface being wider than said inner surface. 2.The tire sidewall of claim 1 wherein said inside annular groove and saidoutside annular groove have a width of about 0.03 inch (0.0762 cm).
 3. Apneumatic tire comprising:(a) a carcass having a pair of bead portions;(b) a tread disposed radially outwardly of said carcass, said treadhaving a ground-contacting surface; (c) a pair of sidewalls extendingradially inward from said tread along outer surfaces of said carcasstoward said bead portions, said sidewalls having outer surfacesextending from said tread radially ground-contacting surface to saidbead portions; (d) a strip, said strip affixed to said outer surface ofone of said sidewalls, said strip being made of a first elastomericcompound; said sidewall being made of a second elastomeric compound;said first elastomeric compound and said second elastomeric compoundbeing of different materials and said outer surface of said one of saidsidewalls includes an annular groove having walls and a base, said stripbeing affixed to said base of said groove in said outer surface of saidsidewall, said strip having an inside side surface and an outside sidesurface spaced from said walls providing an inside annular groove and anoutside annular groove, one side surface of each groove exposing saidfirst elastomeric compound of said strip material, the other sidesurface of each groove exposing said second elastomeric compound of saidsidewall, said side surface of each groove exposing said firstelastomeric compound of said strip material and having an interfacebetween said first elastomeric compound and said second elastomericcompound and said strip having an outer surface and an inner surfacewith said outer surface of said strip being wider than said innersurface.
 4. The pneumatic tire of claim 3 wherein said side surfaces ofsaid strip have indentations near said bottom surface.
 5. The pneumatictire of claim 3 wherein said strip is molded.
 6. The pneumatic tire ofclaim 3 wherein said side surfaces of said strip make an angle ofbetween 45 degrees and 75 degrees with said top surface.
 7. Thepneumatic tire of claim 3 wherein said side surfaces of said strip makean angle of between 55 degrees and 65 degrees with said top surface. 8.The pneumatic tire of claim 3 further comprising:(a) a stain barrier,said stain barrier comprising a portion of said sidewall inwardly ofsaid strip.